[All] Basic Accessibility Support (#713)

* [Core] Add accessibility properties

* [Controls] Add accessibility gallery

* [iOS] Implement accessibility properties

* [Android] Implement accessibilty properties

* [Win] Implement accessibility properties

* [Win] Select ListView item on selected for a11y

* Update docs

* TODO: macOS accessibility

* [iOS] Fix failing UI Tests

7 files changed, 220 insertions, 15 deletions

diff --git a/Xamarin.Forms.Platform.WinRT/CarouselPageRenderer.cs b/Xamarin.Forms.Platform.WinRT/CarouselPageRenderer.cs
index 11f4e09d..33e09399 100644
--- a/Xamarin.Forms.Platform.WinRT/CarouselPageRenderer.cs
+++ b/Xamarin.Forms.Platform.WinRT/CarouselPageRenderer.cs
@@ -70,6 +70,11 @@ namespace Xamarin.Forms.Platform.WinRT
 			return new SizeRequest(result);
 		}
 
+		UIElement IVisualElementRenderer.GetNativeElement()
+		{
+			return null;
+		}
+
 		public void SetElement(VisualElement element)
 		{
 			var newPage = element as CarouselPage;
diff --git a/Xamarin.Forms.Platform.WinRT/IVisualElementRenderer.cs b/Xamarin.Forms.Platform.WinRT/IVisualElementRenderer.cs
index 4db9c1a6..abae812e 100644
--- a/Xamarin.Forms.Platform.WinRT/IVisualElementRenderer.cs
+++ b/Xamarin.Forms.Platform.WinRT/IVisualElementRenderer.cs
@@ -18,6 +18,9 @@ namespace Xamarin.Forms.Platform.WinRT
 		event EventHandler<VisualElementChangedEventArgs> ElementChanged;
 
 		SizeRequest GetDesiredSize(double widthConstraint, double heightConstraint);
+
 		void SetElement(VisualElement element);
+
+		UIElement GetNativeElement();
 	}
 }
\ No newline at end of file
diff --git a/Xamarin.Forms.Platform.WinRT/ListViewRenderer.cs b/Xamarin.Forms.Platform.WinRT/ListViewRenderer.cs
index db581d52..031e2cf3 100644
--- a/Xamarin.Forms.Platform.WinRT/ListViewRenderer.cs
+++ b/Xamarin.Forms.Platform.WinRT/ListViewRenderer.cs
@@ -77,9 +77,6 @@ namespace Xamarin.Forms.Platform.WinRT
 					// and prevented from bubbling up) rather than ListView.ItemClick
 					List.Tapped += ListOnTapped;
 
-					// We also want to watch for the Enter key being pressed for selection
-					List.KeyUp += OnKeyPressed;
-					
 					List.SelectionChanged += OnControlSelectionChanged;
 
 					List.SetBinding(ItemsControl.ItemsSourceProperty, "");
@@ -141,7 +138,6 @@ namespace Xamarin.Forms.Platform.WinRT
 			if (List != null)
 			{
 				List.Tapped -= ListOnTapped;
-				List.KeyUp -= OnKeyPressed;
 
 				List.SelectionChanged -= OnControlSelectionChanged;
 
@@ -508,17 +504,6 @@ namespace Xamarin.Forms.Platform.WinRT
 #endif
 		}
 
-		void OnKeyPressed(object sender, KeyRoutedEventArgs e)
-		{
-			if (e.Key == VirtualKey.Enter)
-			{
-				if (Element.SelectedItem != null && Element.SelectedItem != List.SelectedItem)
-				{
-					((IElementController)Element).SetValueFromRenderer(ListView.SelectedItemProperty, List.SelectedItem);
-				}
-			}
-		}
-
 		void OnControlSelectionChanged(object sender, SelectionChangedEventArgs e)
 		{
 			RestorePreviousSelectedVisual();
@@ -540,6 +525,10 @@ namespace Xamarin.Forms.Platform.WinRT
 				}
 			}
 #endif
+
+			// A11y: Tapped event will not be routed when Narrator is active
+			// Also handles keyboard selection
+			SelectElementItem();
 		}
 
 		FrameworkElement FindElement(object cell)
@@ -553,6 +542,15 @@ namespace Xamarin.Forms.Platform.WinRT
 			return null;
 		}
 
+		void SelectElementItem()
+		{
+			if (List.SelectedItem != null && Element.SelectedItem != List.SelectedItem)
+			{
+				((IElementController)Element).SetValueFromRenderer(ListView.SelectedItemProperty, List?.SelectedItem);
+				OnElementItemSelected(null, new SelectedItemChangedEventArgs(Element?.SelectedItem));
+			}
+		}
+
 #if WINDOWS_UWP
 		void RestorePreviousSelectedVisual()
 		{
diff --git a/Xamarin.Forms.Platform.WinRT/MasterDetailPageRenderer.cs b/Xamarin.Forms.Platform.WinRT/MasterDetailPageRenderer.cs
index 414870cd..dcef680e 100644
--- a/Xamarin.Forms.Platform.WinRT/MasterDetailPageRenderer.cs
+++ b/Xamarin.Forms.Platform.WinRT/MasterDetailPageRenderer.cs
@@ -94,6 +94,11 @@ namespace Xamarin.Forms.Platform.WinRT
 
 		public event EventHandler<VisualElementChangedEventArgs> ElementChanged;
 
+		UIElement IVisualElementRenderer.GetNativeElement()
+		{
+			return null;
+		}
+
 		public SizeRequest GetDesiredSize(double widthConstraint, double heightConstraint)
 		{
 			return new SizeRequest(new Size(Device.Info.ScaledScreenSize.Width, Device.Info.ScaledScreenSize.Height));
diff --git a/Xamarin.Forms.Platform.WinRT/NavigationPageRenderer.cs b/Xamarin.Forms.Platform.WinRT/NavigationPageRenderer.cs
index e7e01843..5229fdcb 100644
--- a/Xamarin.Forms.Platform.WinRT/NavigationPageRenderer.cs
+++ b/Xamarin.Forms.Platform.WinRT/NavigationPageRenderer.cs
@@ -137,6 +137,11 @@ namespace Xamarin.Forms.Platform.WinRT
 			return new SizeRequest(result);
 		}
 
+		UIElement IVisualElementRenderer.GetNativeElement()
+		{
+			return null;
+		}
+
 		public void SetElement(VisualElement element)
 		{
 			if (element != null && !(element is NavigationPage))
diff --git a/Xamarin.Forms.Platform.WinRT/ViewRenderer.cs b/Xamarin.Forms.Platform.WinRT/ViewRenderer.cs
index 148da1b3..0017531f 100644
--- a/Xamarin.Forms.Platform.WinRT/ViewRenderer.cs
+++ b/Xamarin.Forms.Platform.WinRT/ViewRenderer.cs
@@ -1,5 +1,6 @@
 using Windows.UI.Xaml;
 using Windows.UI.Xaml.Automation;
+using Windows.UI.Xaml.Automation.Peers;
 
 #if WINDOWS_UWP
 
@@ -11,6 +12,11 @@ namespace Xamarin.Forms.Platform.WinRT
 {
 	public class ViewRenderer<TElement, TNativeElement> : VisualElementRenderer<TElement, TNativeElement> where TElement : View where TNativeElement : FrameworkElement
 	{
+		string _defaultAutomationPropertiesName;
+		AccessibilityView? _defaultAutomationPropertiesAccessibilityView;
+		string _defaultAutomationPropertiesHelpText;
+		UIElement _defaultAutomationPropertiesLabeledBy;
+
 		protected override void OnElementChanged(ElementChangedEventArgs<TElement> e)
 		{
 			base.OnElementChanged(e);
@@ -33,5 +39,97 @@ namespace Xamarin.Forms.Platform.WinRT
 				Control.SetValue(AutomationProperties.AutomationIdProperty, id);
 			}
 		}
+		protected override void SetAutomationPropertiesName()
+		{
+			if (Control == null)
+			{
+				base.SetAutomationPropertiesName();
+				return;
+			}
+
+			if (Element == null)
+				return;
+
+			if (_defaultAutomationPropertiesName == null)
+				_defaultAutomationPropertiesName = (string)Control.GetValue(AutomationProperties.NameProperty);
+
+			var elemValue = (string)Element.GetValue(Accessibility.NameProperty);
+
+			if (!string.IsNullOrWhiteSpace(elemValue))
+				Control.SetValue(AutomationProperties.NameProperty, elemValue);
+			else
+				Control.SetValue(AutomationProperties.NameProperty, _defaultAutomationPropertiesName);
+		}
+
+		protected override void SetAutomationPropertiesAccessibilityView()
+		{
+			if (Control == null)
+			{
+				base.SetAutomationPropertiesAccessibilityView();
+				return;
+			}
+
+			if (Element == null)
+				return;
+
+			if (!_defaultAutomationPropertiesAccessibilityView.HasValue)
+				_defaultAutomationPropertiesAccessibilityView = (AccessibilityView)Control.GetValue(AutomationProperties.AccessibilityViewProperty);
+
+			var newValue = _defaultAutomationPropertiesAccessibilityView;
+			var elemValue = (bool?)Element.GetValue(Accessibility.IsInAccessibleTreeProperty);
+
+			if (elemValue == true)
+				newValue = AccessibilityView.Content;
+			else if (elemValue == false)
+				newValue = AccessibilityView.Raw;
+
+			Control.SetValue(AutomationProperties.AccessibilityViewProperty, newValue);
+		}
+
+		protected override void SetAutomationPropertiesHelpText()
+		{
+			if (Control == null)
+			{
+				base.SetAutomationPropertiesHelpText();
+				return;
+			}
+
+			if (Element == null)
+				return;
+
+			if (_defaultAutomationPropertiesHelpText == null)
+				_defaultAutomationPropertiesHelpText = (string)Control.GetValue(AutomationProperties.HelpTextProperty);
+
+			var elemValue = (string)Element.GetValue(Accessibility.HintProperty);
+
+			if (!string.IsNullOrWhiteSpace(elemValue))
+				Control.SetValue(AutomationProperties.HelpTextProperty, elemValue);
+			else
+				Control.SetValue(AutomationProperties.HelpTextProperty, _defaultAutomationPropertiesHelpText);
+		}
+
+		protected override void SetAutomationPropertiesLabeledBy()
+		{
+			if (Control == null)
+			{
+				base.SetAutomationPropertiesLabeledBy(); 
+				return;
+			}
+
+			if (Element == null)
+				return;
+
+			if (_defaultAutomationPropertiesLabeledBy == null)
+				_defaultAutomationPropertiesLabeledBy = (UIElement)Control.GetValue(AutomationProperties.LabeledByProperty);
+
+			var elemValue = (VisualElement)Element.GetValue(Accessibility.LabeledByProperty);
+			var renderer = elemValue?.GetOrCreateRenderer();
+			var nativeElement = renderer?.GetNativeElement();
+
+			if (nativeElement != null)
+				Control.SetValue(AutomationProperties.LabeledByProperty, nativeElement);
+			else
+				Control.SetValue(AutomationProperties.LabeledByProperty, _defaultAutomationPropertiesLabeledBy);
+		}
 	}
 }
\ No newline at end of file
diff --git a/Xamarin.Forms.Platform.WinRT/VisualElementRenderer.cs b/Xamarin.Forms.Platform.WinRT/VisualElementRenderer.cs
index b81f73e3..402d1da8 100644
--- a/Xamarin.Forms.Platform.WinRT/VisualElementRenderer.cs
+++ b/Xamarin.Forms.Platform.WinRT/VisualElementRenderer.cs
@@ -4,6 +4,7 @@ using System.ComponentModel;
 using Windows.Foundation;
 using Windows.UI.Xaml;
 using Windows.UI.Xaml.Automation;
+using Windows.UI.Xaml.Automation.Peers;
 using Windows.UI.Xaml.Controls;
 
 #if WINDOWS_UWP
@@ -17,6 +18,10 @@ namespace Xamarin.Forms.Platform.WinRT
 	public class VisualElementRenderer<TElement, TNativeElement> : Panel, IVisualElementRenderer, IDisposable, IEffectControlProvider where TElement : VisualElement
 																																	  where TNativeElement : FrameworkElement
 	{
+		string _defaultAutomationPropertiesName;
+		AccessibilityView? _defaultAutomationPropertiesAccessibilityView;
+		string _defaultAutomationPropertiesHelpText;
+		UIElement _defaultAutomationPropertiesLabeledBy;
 		bool _disposed;
 		EventHandler<VisualElementChangedEventArgs> _elementChangedHandlers;
 		VisualElementTracker<TElement, TNativeElement> _tracker;
@@ -108,6 +113,11 @@ namespace Xamarin.Forms.Platform.WinRT
 			return new SizeRequest(result);
 		}
 
+		public UIElement GetNativeElement()
+		{
+			return Control;
+		}
+
 		public void SetElement(VisualElement element)
 		{
 			TElement oldElement = Element;
@@ -287,6 +297,14 @@ namespace Xamarin.Forms.Platform.WinRT
 				UpdateEnabled();
 			else if (e.PropertyName == VisualElement.BackgroundColorProperty.PropertyName)
 				UpdateBackgroundColor();
+			else if (e.PropertyName == Accessibility.HintProperty.PropertyName)
+				SetAutomationPropertiesHelpText();
+			else if (e.PropertyName == Accessibility.NameProperty.PropertyName)
+				SetAutomationPropertiesName();
+			else if (e.PropertyName == Accessibility.IsInAccessibleTreeProperty.PropertyName)
+				SetAutomationPropertiesAccessibilityView();
+			else if (e.PropertyName == Accessibility.LabeledByProperty.PropertyName)
+				SetAutomationPropertiesLabeledBy();
 		}
 
 		protected virtual void OnRegisterEffect(PlatformEffect effect)
@@ -300,6 +318,75 @@ namespace Xamarin.Forms.Platform.WinRT
 			SetValue(AutomationProperties.AutomationIdProperty, id);
 		}
 
+		protected virtual void SetAutomationPropertiesName()
+		{
+			if (Element == null || Control == null)
+				return;
+
+			if (_defaultAutomationPropertiesName == null)
+				_defaultAutomationPropertiesName = (string)Control.GetValue(AutomationProperties.NameProperty);
+
+			var elemValue = (string)Element.GetValue(Accessibility.NameProperty);
+
+			if (!string.IsNullOrWhiteSpace(elemValue))
+				Control.SetValue(AutomationProperties.NameProperty, elemValue);
+			else
+				Control.SetValue(AutomationProperties.NameProperty, _defaultAutomationPropertiesName);
+		}
+
+		protected virtual void SetAutomationPropertiesAccessibilityView()
+		{
+			if (Element == null || Control == null)
+				return;
+
+			if (!_defaultAutomationPropertiesAccessibilityView.HasValue)
+				_defaultAutomationPropertiesAccessibilityView = (AccessibilityView)Control.GetValue(AutomationProperties.AccessibilityViewProperty);
+
+			var newValue = _defaultAutomationPropertiesAccessibilityView;
+			var elemValue = (bool?)Element.GetValue(Accessibility.IsInAccessibleTreeProperty);
+
+			if (elemValue == true)
+				newValue = AccessibilityView.Content;
+			else if (elemValue == false)
+				newValue = AccessibilityView.Raw;
+
+			Control.SetValue(AutomationProperties.AccessibilityViewProperty, newValue);
+		}
+
+		protected virtual void SetAutomationPropertiesHelpText()
+		{
+			if (Element == null || Control == null)
+				return;
+
+			if (_defaultAutomationPropertiesHelpText == null)
+				_defaultAutomationPropertiesHelpText = (string)Control.GetValue(AutomationProperties.HelpTextProperty);
+
+			var elemValue = (string)Element.GetValue(Accessibility.HintProperty);
+
+			if (!string.IsNullOrWhiteSpace(elemValue))
+				Control.SetValue(AutomationProperties.HelpTextProperty, elemValue);
+			else
+				Control.SetValue(AutomationProperties.HelpTextProperty, _defaultAutomationPropertiesHelpText);
+		}
+
+		protected virtual void SetAutomationPropertiesLabeledBy()
+		{
+			if (Element == null || Control == null)
+				return;
+
+			if (_defaultAutomationPropertiesLabeledBy == null)
+				_defaultAutomationPropertiesLabeledBy = (UIElement)Control.GetValue(AutomationProperties.LabeledByProperty);
+
+			var elemValue = (VisualElement)Element.GetValue(Accessibility.LabeledByProperty);
+			var renderer = elemValue?.GetOrCreateRenderer();
+			var nativeElement = renderer?.GetNativeElement();
+
+			if (nativeElement != null)
+				Control.SetValue(AutomationProperties.LabeledByProperty, nativeElement);
+			else
+				Control.SetValue(AutomationProperties.LabeledByProperty, _defaultAutomationPropertiesLabeledBy);
+		}
+
 		protected void SetNativeControl(TNativeElement control)
 		{
 			TNativeElement oldControl = Control;
@@ -367,6 +454,10 @@ namespace Xamarin.Forms.Platform.WinRT
 		protected virtual void UpdateNativeControl()
 		{
 			UpdateEnabled();
+			SetAutomationPropertiesHelpText();
+			SetAutomationPropertiesName();
+			SetAutomationPropertiesAccessibilityView();
+			SetAutomationPropertiesLabeledBy();
 		}
 
 		internal virtual void OnElementFocusChangeRequested(object sender, VisualElement.FocusRequestArgs args)